Ch 8 - Growth & the Means to sexual reproduction

1. Ch 8 - Growth & the Means to sexual reproduction

2. Why do cells divide?

3. Replacement of skin cells Deadcells Epidermis, the outer layer of the skin Dividingcells Dermis Figure 8.11B

4. Plasmamembrane • Asexual reproduction of a prokaryotic cell Cell wall Division intotwo cells Figure 8.3A

5. Mitosis = asexual reproduction

6. What do all cells need to function?

7. DNA • )

9. genome • Sum of genetic information • Made of autosomes and sex chromosomes • Chromosomes occur in homologous pairs in sexually reproducing organisms • Chromosome number of an organism can be DIploid or HAPloid

11. Karyotype – array of chromosomes an organism has

13. Cell Cycle

14. The cell division party!!

15. Interphase • G1 • S • G2 • G0

17. End results of Mitosis • 1 cell has become 2 • New cells made • Genetic information has stayed the same • Number of chromosomes has stayed the same in each new cell

18. Regulation of Mitosis/growth • Cell checkpoints and feedback mechanisms • Growth hormones • Density dependence

19. Growth factors tell the cell to divide Growth factor Plasma membrane Relayproteins Receptor protein Signal transduction pathway Figure 8.8B

20. This is called density-dependent inhibition • Cells continue dividing until they touch one another Cells anchor to dish surface and divide. When cells have formed a complete single layer, they stop dividing (density-dependent inhibition). If some cells are scraped away, the remaining cells divide to fill the dish with a single layer and then stop (density-dependent inhibition). Figure 8.8A

21. Cancer • Cells Behaving Badly • unlimited division, no apoptosis • Feedback signals not working • Benign vs. malignant • Metastasize • tumor

22. Malignant tumors can invade other tissues and may kill the organism Lymphvessels Tumor Glandulartissue Metastasis 1 A tumor grows from a single cancer cell. 2 Cancer cells invade neighboring tissue. 3 Cancer cells spread through lymph and blood vessels to other parts of the body. Figure 8.10

23. Formation of Sex Cells • Must have haploid number of chromosomes in gametes • Reduction/Division • Must reduce the diploid number by 1/2 • This is Meiosis

24. Stages … • One Interphase and chromosome doubling • Meiosis I and Meiosis II • 2 cytokinesis • End result – 4 gametes with ½ chromosome number

27. Diploid to haploid • At the end of Meiosis I, 2 cells with ½ the chromosome # (one of each homologous pair) • Those chromosomes are still made of pairs of chromatids which still need to be pulled apart

28. Meiosis II • Simply, mitosis again

30. Genetic Diversity • Crossing over • Random line-up on metaphase plate • Independent assortment • Union of individual gametes to form zygote

31. Which cells undergo Mitosis? Meiosis?

32. Haploid gametes (n = 23) Egg cell • The human life cycle Sperm cell MEIOSIS FERTILIZATION Diploidzygote (2n = 46) Multicellulardiploid adults (2n = 46) Mitosis anddevelopment Figure 8.13

33. Meiosis • Forms sperm • Spermatogenesis • Forms eggs • Oogenesis

35. Chromosome Errors • Deletion • Inversion • Translocation • Sticky cromosomes